Answer:
9
Step-by-step explanation:
Equation
Sum = s  = 180*(n - 2)
Solution
1260 = 180*(n - 2) Â Â Â Â Â Â Divide by 180
1260 / 180 = 180 * (n -2 ) / 180
7 = n - 2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Add 2 to both sides
9 = n      Â
Answer
The polygon has 9 sides.